1. Field of the Invention
This invention relates to a method and apparatus for coating elongated tubes and strips by sputtering.
2. Description of the Prior Art
Typical commercial sputtering equipment using flat-circular sputtering targets can neither accomodate nor sputter a uniform coating onto a tubular workpiece, especially elongated workpieces.
An apparatus for reactively sputtering onto tubes was recently described in an article by Harding et al. in the Journal of Vacuum Science Technology, Vol. 13, No. 5, page 1073, (1976). The apparatus in this article deposits a coating along the full length of a rotating tubular workpiece, but a full-length rod cathode or a cathode equivalent to the length of the rotating workpiece was required. The lack of uniformity of the coating along the length of the rotating workpiece is mentioned as a problem in this article.